1. Field of the Invention
The present invention relates to a wireless local area network (LAN), more particularly to a method, access point, and system for detecting rogue access points and preventing wireless terminals from connecting with them.
2. Description of the Related Art
A typical corporate wireless LAN system has the structure shown in FIG. 1, in which wireless LAN terminals 1-1 to 1-N access a wired LAN 2 through access points 3-1 to 3-M, where M and N are positive integers. Japanese Patent Application Publication No. 2000-312162, for example, describes wireless LAN systems of this type.
The wireless LAN terminals 1-n (where n is from 1 to N) and the access points 3-m (where m is from 1 to M) are wirelessly connected without the need of transmission cables, so the terminals have greater mobility than in a wired network. Wireless LAN systems are therefore becoming a popular type of corporate network infrastructure.
However, wireless signals pass through the walls of corporate buildings in which wireless LANs are located, so if a rogue access point 4 is set up outside a building 5 by a third party as in FIG. 2 with the intention of eavesdropping, it is difficult for a wireless LAN terminal 1-n to tell whether this access point is legitimate or not.
To address this problem, the present applicant has proposed a method by which a legitimate access point can detect rogue access points around it (Japanese Patent Application No. 2006-060094). As wireless LAN systems are not connected by cables, however, it is difficult for a wireless LAN terminal to determine which access point it has connected to, and wireless LAN systems do not provide means by which an access point can notify a wireless LAN terminal that an access point is not legitimate, so even when a legitimate access point 3-m detects a rogue access point 4 nearby, that does not prevent a wireless LAN terminal 1-n from inadvertently connecting with the rogue access point 4, as illustrated in FIG. 2.
There is thus a great need for a method, system, and access point that can detect rogue access points and prevent wireless terminals from connecting with them.